The Lipoprotein (a) test measures the level of lipoprotein(a), often abbreviated as Lp(a), in your blood. Lp(a) is a type of lipoprotein, similar to LDL (“bad cholesterol”), that carries cholesterol and fats through the bloodstream. Elevated Lp(a) levels can increase the risk of heart disease, stroke, and atherosclerosis (hardening of the arteries).